How to bend wood like this - Outdoor furniture project

[Maurice Mcmurry]

I use West System epoxy thickened to paste consistency with collodial silica. It wets out amazingly well without running all over the place. The exceptional wet out characteristics insure that it will stick strong whether its quite thick or very thin.

[Alan Lightstone]

I use West System epoxy thickened to paste consistency with collodial silica. It wets out amazingly well without running all over the place. The exceptional wet out characteristics insure that it will stick strong whether its quite thick or very thin.

I tried that route yesterday with a couple of layers. Going to take off the clamps today (48 hrs). I'll then see how much springback (if any) I get from the first two inside layers. Strengthwise, I don't think I would be able to glue all 10 laminates together and then bend on the form. So my game plan is to do 2-3 layers at a time, perhaps up to about 4 layers, then winch in place and place clamps.

I also bought some West Systems extra slow hardener to get really long working time.

[Alan Lightstone]

OK. That's it. Waving the white flag. This just isn't working for me. With my setup, physical strength, etc... Steam bending or bent laminations are out for this chair. The pieces have springback, gaps between lamination, uneven height. Just not at all usable and a tremendous waste of wood. Was a somewhat interesting, but mostly frustrating exercise. Spent a good deal of money on winch/straps/mdf/ etc... And have taken up most of my workshop with jigs, etc... for this. Anyone need 2 steam generators and an extra long steam box (sigh...)

So I still need to make the chair (we've already bought the expensive cushions and really need replacement chairs out there. Building them like the originals (solid wood, but not using teak) is the new plan. A whole new set of questions pops up then.

To refresh everyone who's been so helpful memories, this is what the chair needs to look like:
Chair with Seams 1.jpg

The most difficult part is the chair back, which is 5-1/2" tall and 1-1/2" thick. I can easily make a pattern of the shape and rough cut it on my bandsaw. But how do I smooth out the profile with a router table when it's that tall? Are there pattern bits that long that can safely be used on a router? No shaper here. I need to make 4 chairs, so will need to make a bunch of identical pieces. And my initial concern about lining up the pieces for gluing still seems difficult (but not impossible.)

So mostly concerns about routing the pieces identically and smoothly. Both the inside and outside curves.

[Kevin Jenness]

Forget pattern routing. Do the joinery and assembly, then saw the parts out as accurately as possible and clean up the faces. In my shop I would use an edge sander.

[Mike King]

I realize you are frustrated, but the best approach to achieve that shape is bent lamination. If you really want to get it to work, it seems like you need some expert instruction. Here's the solution to that:

https://schoolofwoodwork.com/event/2...gnfabrication/

Kelly Parker interned with Michael Fortune and teaches woodworking with him quite frequently. If you were to sign up for that class and take your project there, Kelly can help you figure out the caul, padding, and clamping that will allow you to complete your project.

Mike

[Mike King]

An alternate way to achieve the curve would be to Cooper the bend. But rather than grain following the curve, the grain would be vertical (I don't think it would be a good idea to glue end grain to end grain, especially outdoors). You would have a fair amount of hand work to fair the curves.

This brings up a design question: what is the radius of the curve for your chair back? Have you built a prototype to test the comfort of your design? Generally speaking, a comfortable radius on a seat back is 18+ inches.

[Michael Burnside]

One thought I had was what about building them in layers of say 1 to 1-1/2" tall and stacking them. You could easily build a template, rough cut on the bandsaw and flush trim, then stack them until you reached the final height. I guess after that you could veneer and hide the layering or simply lean into it, which is what I would do.

I personally applaud you for your efforts as I would have waived the flag ages ago. I'm a serious hobbyist and once all the fun is gone and it becomes a job, I've done something wrong...

[Alan Lightstone]

An alternate way to achieve the curve would be to Cooper the bend. But rather than grain following the curve, the grain would be vertical (I don't think it would be a good idea to glue end grain to end grain, especially outdoors). You would have a fair amount of hand work to fair the curves.

This brings up a design question: what is the radius of the curve for your chair back? Have you built a prototype to test the comfort of your design? Generally speaking, a comfortable radius on a seat back is 18+ inches.

A really interesting suggestion, Mike. Out-of-the-box thinking. Don't think I'd like the look, but very interesting.

[Alan Lightstone]

One thought I had was what about building them in layers of say 1 to 1-1/2" tall and stacking them. You could easily build a template, rough cut on the bandsaw and flush trim, then stack them until you reached the final height. I guess after that you could veneer and hide the layering or simply lean into it, which is what I would do.

I personally applaud you for your efforts as I would have waived the flag ages ago. I'm a serious hobbyist and once all the fun is gone and it becomes a job, I've done something wrong...

Probably my approach. I can probably find a long-enough pattern bit to do this in two 2-3/4" tall layers.

Of course that still leaves the problem of gluing those curves together (dominos I would think), and repeatability.

[Michael Burnside]

Probably my approach. I can probably find a long-enough pattern bit to do this in two 2-3/4" tall layers.

Of course that still leaves the problem of gluing those curves together (dominos I would think), and repeatability.

They won't be curves, they will be 30 or 45 degree miters that you will make curves after the glue has dried. I would make a template that is the exact curve of the entire chair back. Do NOT use a Domino unless you are 100% sure you won't expose them when making the curves. Personally I would offset the wood so it's long-grain adhesion that is the strength and just use some CA glue and wood-glue combo to hold the miters while they dry. No dominos needed.

I'm actually working on a similar design for a console that is curved on one end. It's 16" deep so I will be gluing 16 1" curves together. So, misery loves company

[Mike King]

They won't be curves, they will be 30 or 45 degree miters that you will make curves after the glue has dried. I would make a template that is the exact curve of the entire chair back. Do NOT use a Domino unless you are 100% sure you won't expose them when making the curves. Personally I would offset the wood so it's long-grain adhesion that is the strength and just use some CA glue and wood-glue combo to hold the miters while they dry. No dominos needed.

I'm actually working on a similar design for a console that is curved on one end. It's 16" deep so I will be gluing 16 1" curves together. So, misery loves company

My first curved piece was an A/V console with curved sides that is roughly 20" deep and veneered. I designed and made it with the assistance of Michael Fortune. To make the sides, I kerf-bent ¾" MDF around a form in a vacuum bag, then used the form to veneer the MDF. It was very successful.

IMG_1906.jpg

[Mike King]

That photo posted upside down. Who knows what is wrong with this forum software...

[Kevin Jenness]

If you feel you need to bricklay and pattern-rout stacked layers in order to get an accurate curve I suggest keeping the thickness down and use 3 or 4 layers as trimming with a long router bit invites chatter. Saw as close to the line as possible. You may get some router tearout near the joints due to grain direction reversal and you will have a busy looking assembly. For exterior use reinforcing the endgrain joints with dominos and epoxy is a good idea.

Bricklaying will give a somewhat stronger result than full height segments. Veneering over the bricklaid assembly will strengthen the back further. You will have to decide if the extra work is worth it. The original makers kept it simple and I would do the same, segmenting the curve in full height pieces with splined and epoxied joints, then sawing and sanding.

The strip laminated approach can work, you need thicker cauls and more clamping force.

[Mike King]

...
The strip laminated approach can work, you need thicker cauls and more clamping force.

And more clamps.

[Kevin Jenness]

And more clamps.

Not necessarily. Pneumatic pressure is an option (Fine Woodworking #63 p. 83, Pneumatic Lamination). If one runs short of clamps threaded rod is an alternative as shown here. https://woodarchivist.com/3725-makin...nation-curves/ In any event the project needs enough force distributed evenly through cauls to pull the laminates together gap-free.